1. Brief Description of the Invention
The present invention relates to a device and method for bending a flange extending from a workpiece. More specifically, the invention relates to a device and method for selectively altering the angularity of a variety of extruded and L-shaped sheet metal parts.
2. Description of the Related Art
Three general approaches exist for angularly altering the flange of a workpiece. According to a first approach, numerous brake bars are selectively placed in a press brake in order to produce different workpieces having varying angularly bent flanges. Each brake bar must be manufactured with an angled portion reasonably close to the desired angular bend of the flange of the workpiece in order to obtain the support required for bending. Such support is necessary to ensure that the point of bend during the angle altering operation is as close as possible to the intersection point of the flange with the workpiece. This ensures that both the flange and the cap of a workpiece maintain a substantially planar shape. There are a number of drawbacks to this approach. First, an extensive catalog of brake bars is necessary which may become very expensive. In addition, in situations where a number of different parts must be manufactured using the same press brake, this approach requires considerable down time for removing and installing various brake bars.
According to a second approach, a brake bar similar to the one depicted in FIG. 3 can be made with a non-specific or generic angle and can be used to form a variety of angled parts. This approach sacrifices the quality of an altered part by reducing or eliminating the necessary support to achieve the proper point of bend. With the second approach, bending may occur at an improper location, or a roll rather than a bend may be formed in the flange.
According to a third approach, a form die (shown in FIG. 4) is used and includes a pair of mating surfaces which are urged together to bend the flange therebetween. A drawback of this approach is that a separate die is required for each part having a different angular bend.
Another drawback common to each of the above described approaches is that the dies used are manufactured to accommodate parts of specific thicknesses. Thus, in order to achieve the same angular alteration in a number of parts having various thicknesses, it is necessary to use a different brake bar tailored to the thickness of each part.
The present invention provides an improved device and method for altering the angular dimensions of a workpiece. According to the present invention, a single brake bar that can accommodate workpieces having various thicknesses can be used to bend the flange of a workpiece to an infinite number of angles.
Advantages of the invention are set forth in part in the description which follows, and in part will be obvious in the description, or may be learned by practice of the invention.